Safety signal



July 28, 1925. 1,547,502

G. A. L. LAJOIE SAFETY SIGNAL Filed Dec, 12, 1924 v V I Hedge/4i 0/018,

A Home Vs vention of accidents.

Patented July 2 8, 1925.

UNITED STA TES PATENT OFFICE.

SAFETY SIGNAL.

Application filed December 12, 1924. Serial No. 755,417. J

To all whom it may concern.

Be it known that I, GEORGE A. L. LAJOIE, a subject of the King of Great Britain, and resident of the city of Montreal, Province of Quebec, Dominion of Canada, have invented certain new and useful Improvements in Safety Signals; and I do hereby declare that the following is a full, clear, and exact description thereof.

This invention relates to safety signals adapted to be mounted upon tram cars, railroad cars and other like conveyances for pre- The object of the present invention is to reduce the hazard connected with persons crossing in rear of tram cars and railway trains by providing a warning signal on' each tram car or on the last car of a train at a conspicuous point, which will warn persons in the immediate vicinity of the approach of a car or train of cars moving in the opposite direction and constituting a menace to any one attempting to cross the tracks at that particular time.

To this end myinvention broadly stated consists of a warning signal adapted to be mounted upon the rear or adjacent the rear of a tram car or railwa train and means for automatically operating the saidsignal when another car movin in the opposite direction approaches within a given distance,

i such means being carried jointly by the two cars. The invention also includes manually operated means for operating the signal independently of the automatic means.

More comprehensively stated the invention consists of the combination, construction and particular arrangement of the parts hereinafter described and illustrated and pointed out in the claims,

"For full comprehension of my invention reference must be had to the accompanying drawings in which similar-reference characters indicate the same parts, and wherein:

Figure 1 is a plan view of two tram cars moving in opposite directions and each having my improved safety signal applied thereto, each car being in position to actuate the signal of the other car;

Figure 2 is a diagrammatic view of the electric circuits by which the signal proper is operated.

' Figure 3 is a fragmentary perspective view of the front ends of two tram cars having a equipped with my invention in the of passing each other; and

,Figure 4 is a detail-view of the means for manually operating the signal.

The accompanying drawings illustrate the preferred embodiment of my invention for use on tram cars and the equipment for each car or train of cars is the same irrespective of the direction of travel of such car or cars and so constructed and arranged that when two cars or trains of cars moving in opposite directions reach a relative proximity constituting a menace to persons attempting to cross the car tracks in rear of either car the signals on both cars or trains of cars will be operated.

In Figure 1 two cars moving in opposite directions are indicated at A and B respectively and each is provided with. a warning signal 2 at its rear end.

The means for actuating each signal is the same and consists of a normally open electrical alarm circuit 0 having the signal as a component part thereof, a normally open controlled by the relay E, means indicated at- G whereby the approach of a car automatically closes the controlling circuit, and manually operated means H for closing the alarm circuit independently of the controlling circuit. i

The alarm circuit 0 comprises the following connected in series: a source of power (P, the signal 0 consistsing of a bell and red lamp, and a pair of spring contacts C with each other and being normally separated by a non-conductingelement forming a component part of the time relay F. r

The controlling circuit D includes as a tendency to spring into engagement component part thereof a photo-electric cell i ,D. This cell is preferably located at the front of each car as indicated in Figure 3 and coacts with a headlight G on the other car, the cell and headlight being so relatively positioned that the latter will not interfere with the vision of the motorman and yet will project a beam' of light upon the cell when the cars have-reached a relative proximity in which one constitutes a menacetopersons crossing the railway tracks-in rear of the other. Each cell is protected from or hood I) mounted upon an adjacent portion of the car.

When-a beam of light is projected upon the photo-electric cell the controlling c1rcuit is closed and the time relay energized. If desired the photoelectric cell may be connected in series with a Source of power and the time relay F or, as illustrated, a highly sensitive instantaneous relay E of the Ruben type may also be incorporated to ensure that the time relay will function when the controlling circuit is closed. The addition of the Ruben relay, although not absolutely essential has proved advantageous owing to the fact that theamperage of the exciting current which flows through the photo-electric cell is small and requires a more or less sensitive time rela and the Ruben relay is adapted to raise t e amperage of the excit-- ing current sulficiently to operate a stronger and less sensitive time relay with ease.

The Ruben relay comprises a vacuum tube containing a filament E grid E and an expansible thermo-active anode E carrying a movable contact E adapted to, at times, engage a second contact E". The filament circuit is indicated at E the anode circuit at E and thetime relay energizing circuit at E I The filament and the anode are connected to any convenient source of power E and the circuit of each is constantly closed, the current flow through the filament E and anode E maintaining the contacts E and E in normal positions out of contact with each other. These contacts only move into relative engagement when the normal discharge of electrons from the filament to the anode is increased, the increase causing suflicient expansion of the anode to permit the movable contact E to engage the contact E", as will be hereinafter described.

The time relay F may be of any desired construction. That illustrated consists of a solenoid having an armature connected at one end to the non-conducting element F normally separating the spring contacts in the alarm circuit, and at its opposite end to a collapsible air chamber F having check valves (not shown) constructed and arranged to permit of quick egress and slow incss of the air fronrand into the chamber.

In order to permit of the safet signal being operated independently of t e automatic control, the alarm circuit C is provided with a shunt 0 around the time relay,

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the shunt including a normally open pushbutton switch C which is located in the handle of the usual controller at the front of the car as indicated in Figure l.

The photo-electric cell may be composed of selenium, telurium or any other substance adapted to act as a conductorof electricity when subjected to light above a given in follows:

When two cars moving in dpposite direca menace to persons attempting to cross the car tracks in rear of either car the s1gnal on each car is operated as follows:

tions reach a relative proximity constituting The beam of light from the headlight G of one car is projected upon the photo-electric cell 1) in the controlling circuit 1) of the other car and closes the latter causin an increase in the discharge of electrons rom the filament E and consequently expansion of the'anode E". This expansion permits the movable contact E to engage contact E and close the time relay energizing circuit E. The solenoid F at once withdraws the nonconducting element F from position between the contacts C permitting them to spring into relative engagement closing the alarm or signal circuit and actuating the safety signal.

What I claim is as follows l. The combination of a vehicle, a safety signal mounted thereon, a second vehicle movable parallel to the first vehicle but in the opposite direction thereto, means upon the first vehicle for actuating the signal, and means for controlling the actuatingmeans, said last-mentioned means including a photo-electric cell'carried by the first vehicle and a light projector carried by the second approach of another vehicle moving in the opposite direction, means carried by the first vehlcle conslstin of a normally openelectric alarm circuit including-said signal, a'

normally open controllin circuit, a time re- 1237 included in both o said circuits and a apted to close the alarm circuit when the controlling circuit is closed, and a photoelectric cell included in said controlling circuit and adapted to close the same when subjected to light of suflicient intensity, and means carried by said second vehicle for projecting a beam of light upon said cell.

3. The combination of two vehicles movable parallel to each other in opposite directions, a signal mounted upon one vehicle for indicatingthe approach of the other vehicle, and means for automatically actuating the said signal, said means being carried jointly by the vehicles and consisting of open alarm circuit including saidgsignal; a time relay adapted to open and close said circuit; a highly sensitive instantaneous rea normallyv lay adapted to energize the time relay; a

photo-electric cell connected to said highly sensitive relay, and a light projectoradapted to'project a beam of light upon said cell 6 when the vehicles come within a given distance of each other. a.

4. The combination of two vehicles movable parallel toeach other in opposite directions; a signal mounted upon one vehicle for indicating the approach of the other vehicle, and means for automatically actuating the said signal, said means being carried jointly by the vehicles and consisting of an alarm circuit including a signal, a source of power, and a pair of contacts, a time relay adapted to normally maintain the contacts in positions out of engagement with each other. said relay consisting of a solenoid having an armature, the movement of which is con trolled by a definite time element, said armature being adapted to normally separate said contacts; a highly sensitive instantaneous relay adapted .to energize the time relay, said instantaneous relay consisting of a vacuum tubecontaining a filament, grid, a fixed contact and a movable contact movable to and from engagement with the fixed contact; a thermo-actlve anode adapted to at times impart movement to the movable contact, said contacts being connected to the said solenoid; means connecting the filament and anode to a-source of power; a control- .ling circuit connected to the instantaneous relay and including a photo-electric cell, and

of light upon said cell when the vehicles come within a given distance of each other.

5. The combination of two vehicles movable parallel to each other in opposite directions; a signal mounted upon one vehicle for indicating the approach of the other vehicle, and means for automatically actuating the said signal, said means being carried jointly by the vehicles and consistmg of an alarm circuit including a signal, a source of power, and a pair of contacts; a time relay adapted to normally maintain the contacts in positions out of engagement with each other, said relav consisting of a solenoid having an armature, the movement of which is controlled by a definite time element, said armature being adapted to normally'sep- -aratersaid cont-acts, a highly sensitive instantaneous rela adapted to energize the a light projector adapted to project a beamtimg relay; 'sai instantaneous relay consisting of a vacuum tube containing a filament, grid, a fixed contact and a movable contact movable to and from engagement with the fixed contact; a thermo-active anode adapted to at times im'part'movement to the movable contact, said contacts being connected to the said solenoid; means connecting the filament and anode to a source of power; a controlling circuit connected to the instantaneous relay and including a photoelectric cell, and a light projector adapted to project a beam of light upon said cell when the vehicles come within a given distance of each other, and means for operating the signal independently of the automatic means, consisting of'a shunt around said pair of contacts, and a switch in the shunt. 4

6. The combination of an element to be actuated, and means for electrically operating the same, consisting of a normally open electric circuit including a source of power and connected to said element; a photoelectric cell in the circuit, said cell being adapted to close the circuit when subjected to light-in excess. of a given intensity, and a light projecting element adaptedat times to project a beam of light upon said cell, said photo-electric cell and the light projecting element being both movable in parallel paths and in opposite directions to each other. i i

7. Thecombination of a vehicle, a safety signal mounted thereon, a second vehicle movable parallel to the first vehicle but in the opposite direction thereto, means upon the first vehicle for actuating the signal,

and means for controlling the actuating means, said last-mentioned means including a photo-electric cell carried by the first vehicle, alight projector carried by the second vehicle, the latter being adapted to project a beam of light upon said cell when approaching the same and within a predetermined distance therefrom, and means for manually actuating the signal independently of said cell and light projector.

Intestimony whereof I have signed my name to this specification in the presence of two witnesses.

GEORGE A. LAJOIE.

Witnesses:

GORDON G. Cooxn, "Hannmm MoDoNALn. 

